The invention relates to a device for electrical interconnection of cells of a battery pack by means of cell connectors, and to a battery pack, in particular as an energy store for electric-motor traction and stationary applications.
Document WO 2009/080148 A2 discloses cell connectors in the form of a solid high-current bridging bolt, which is perforated at both ends, between mutually adjacent cell poles of opposite polarities of individual electrochemical cells which can be connected in series to form the battery pack. Compensation sleeves are inserted into the holes in each cell connector, the external diameter of which compensation sleeves is smaller than and the axial length of which compensation sleeves is longer than the respective hole. The freely projecting poles of the cells engage in these sleeves. In this case, each of the compensation sleeves is shifted within its hole on the basis of the manufacturing-dependent tolerances of the pole positions. The compensation sleeves which have been positioned individually in this way are then welded on one side to their cell poles and on the other side to the cell connector. Because of the tolerance compensation via the sleeves which can initially still be shifted in the cell connector, the cells are thus admittedly connected to one another without any mechanical force being introduced; however, because of the solid cell connectors, there is a threat of considerable destructive forces if the cell poles are shifted as a result of heating during operation after the sleeves have been firmly welded. In addition, this cell interconnection does not allow battery management without the additional use of measurement and control lines which have to be connected separately to the cell poles.
The last-mentioned disadvantage is overcome by a circuit board in DE 1 98 10 746 B4. The conductor tracks formed thereon lead from the cell poles, which are placed along the edge of the board, to the central area of the board, which is fitted with a circuit for battery management, and to shunts for matching the states of charge of the individual cells to one another, as well as to multiple plugs as data interfaces. The conductor tracks are plugged onto the cell poles, which end on a plane, with contact being made, in holes in the board. Bolt-like drilled-through cell connectors are plugged onto in each case two cell poles, and this two-layer arrangement of cell connectors and a circuit board located underneath them is finally braced against the ends of the cells, by means of screw connections on the cell poles. Because the circuit board is in each case rigidly screwed between the solid cell connectors and the cell ends, being borne in a manner which is often over defined, while use results in vibrations and temperature-dependent forces from the cells acting via the board on the cell connectors, a flexible material is chosen for the board. However, this involves the risk of conductor track fractures particularly in the immediate vicinity of the pole screw connections, and therefore the risk of failure of the entire battery pack of a rechargeable traction battery such as this, because the battery management means no longer operate correctly.